diff --git a/pkgs/applications/audio/clementine/default.nix b/pkgs/applications/audio/clementine/default.nix
index 0a374c26142..3fdf98da325 100644
--- a/pkgs/applications/audio/clementine/default.nix
+++ b/pkgs/applications/audio/clementine/default.nix
@@ -77,7 +77,7 @@ let
     inherit src patches nativeBuildInputs postPatch;
 
     # gst_plugins needed for setup-hooks
-    buildInputs = buildInputs ++ [ makeWrapper gst_plugins ];
+    buildInputs = buildInputs ++ [ makeWrapper ] ++ gst_plugins;
 
     cmakeFlags = [ "-DUSE_SYSTEM_PROJECTM=ON" ];
 
diff --git a/pkgs/applications/audio/cmus/default.nix b/pkgs/applications/audio/cmus/default.nix
index b88951c0fc5..023e35bd787 100644
--- a/pkgs/applications/audio/cmus/default.nix
+++ b/pkgs/applications/audio/cmus/default.nix
@@ -122,7 +122,7 @@ stdenv.mkDerivation rec {
   buildInputs = [ ncurses ]
     ++ stdenv.lib.optional stdenv.cc.isClang clangGCC
     ++ stdenv.lib.optionals stdenv.isDarwin [ libiconv CoreAudio ]
-    ++ concatMap (a: a.deps) opts;
+    ++ flatten (concatMap (a: a.deps) opts);
 
   makeFlags = [ "LD=$(CC)" ];
 
diff --git a/pkgs/applications/editors/emacs-modes/libgenerated.nix b/pkgs/applications/editors/emacs-modes/libgenerated.nix
index 0529fce2b16..57bccc60818 100644
--- a/pkgs/applications/editors/emacs-modes/libgenerated.nix
+++ b/pkgs/applications/editors/emacs-modes/libgenerated.nix
@@ -77,7 +77,7 @@ in {
                 url = "https://raw.githubusercontent.com/melpa/melpa/${commit}/recipes/${ename}";
                 inherit sha256;
               };
-            packageRequires = lib.optional (! isNull deps)
+            packageRequires = lib.optionals (! isNull deps)
               (map (dep: pkgargs.${dep} or self.${dep} or null)
                    deps);
             meta = (sourceArgs.meta or {}) // {
diff --git a/pkgs/applications/editors/yi/wrapper.nix b/pkgs/applications/editors/yi/wrapper.nix
index 0f3cd7d136a..243690bc263 100644
--- a/pkgs/applications/editors/yi/wrapper.nix
+++ b/pkgs/applications/editors/yi/wrapper.nix
@@ -21,7 +21,7 @@ stdenv.mkDerivation {
   '';
 
   # For hacking purposes
-  env = yiEnv;
+  passthru.env = yiEnv;
 
   meta = with stdenv.lib; {
     description = "Allows Yi to find libraries and the compiler easily";
diff --git a/pkgs/applications/misc/gollum/default.nix b/pkgs/applications/misc/gollum/default.nix
index e9a177ee193..251e84f04c3 100644
--- a/pkgs/applications/misc/gollum/default.nix
+++ b/pkgs/applications/misc/gollum/default.nix
@@ -8,15 +8,15 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ makeWrapper ];
 
-  env = bundlerEnv {
-    name = "${pname}-${version}-gems";
-    inherit pname ruby;
-    gemdir = ./.;
-  };
-
   phases = [ "installPhase" ];
 
-  installPhase = ''
+  installPhase = let
+    env = bundlerEnv {
+      name = "${pname}-${version}-gems";
+      inherit pname ruby;
+      gemdir = ./.;
+    };
+  in ''
     mkdir -p $out/bin
     makeWrapper ${env}/bin/gollum $out/bin/gollum \
       --prefix PATH ":" ${stdenv.lib.makeBinPath [ git ]}
diff --git a/pkgs/applications/networking/instant-messengers/mikutter/default.nix b/pkgs/applications/networking/instant-messengers/mikutter/default.nix
index 5778a2dea3b..7d2037d16a7 100644
--- a/pkgs/applications/networking/instant-messengers/mikutter/default.nix
+++ b/pkgs/applications/networking/instant-messengers/mikutter/default.nix
@@ -27,13 +27,6 @@ stdenv.mkDerivation rec {
     sha256 = "0nx14vlp7p69m2vw0s6kbiyymsfq0r2jd4nm0v5c4xb9avkpgc8g";
   };
 
-  env = bundlerEnv {
-    name = "mikutter-${version}-gems";
-    gemdir = ./.;
-
-    inherit ruby;
-  };
-
   buildInputs = [ alsaUtils libnotify which gtk2 ruby atk gobject-introspection ];
   nativeBuildInputs = [ wrapGAppsHook ];
 
@@ -44,7 +37,14 @@ stdenv.mkDerivation rec {
     rm -rf vendor
   '';
 
-  installPhase = ''
+  installPhase = let
+    env = bundlerEnv {
+      name = "mikutter-${version}-gems";
+      gemdir = ./.;
+
+      inherit ruby;
+    };
+  in ''
     install -v -D -m644 README $out/share/doc/mikutter/README
     install -v -D -m644 LICENSE $out/share/doc/mikutter/LICENSE
     rm -v README LICENSE
diff --git a/pkgs/desktops/deepin/deepin-icon-theme/default.nix b/pkgs/desktops/deepin/deepin-icon-theme/default.nix
index f8258a1d8cd..b6b9feb410b 100644
--- a/pkgs/desktops/deepin/deepin-icon-theme/default.nix
+++ b/pkgs/desktops/deepin/deepin-icon-theme/default.nix
@@ -32,7 +32,7 @@ stdenv.mkDerivation rec {
   '';
 
   buildTargets = "all hicolor-links";
-  installTargets = "install-icons install-cursors";
+  installTargets = [ "install-icons" "install-cursors" ];
   installFlags = [ "PREFIX=${placeholder "out"}" ];
 
   postInstall = ''
diff --git a/pkgs/development/compilers/elm/makeDotElm.nix b/pkgs/development/compilers/elm/makeDotElm.nix
index 3ceaae450f0..0831d382c4b 100644
--- a/pkgs/development/compilers/elm/makeDotElm.nix
+++ b/pkgs/development/compilers/elm/makeDotElm.nix
@@ -11,13 +11,10 @@ ver: deps:
                    inherit (info) sha256;
                  };
 
-                 phases = [ "unpackPhase" "installPhase" ];
-
                  installPhase = ''
                    mkdir -p $out
                    cp -r * $out
                  '';
-
                };
              in ''
                mkdir -p .elm/${ver}/packages/${name}
diff --git a/pkgs/development/compilers/ghc/8.8.1.nix b/pkgs/development/compilers/ghc/8.8.1.nix
index 6872cea4e2a..9e95ba0de2b 100644
--- a/pkgs/development/compilers/ghc/8.8.1.nix
+++ b/pkgs/development/compilers/ghc/8.8.1.nix
@@ -73,7 +73,7 @@ let
   '';
 
   # Splicer will pull out correct variations
-  libDeps = platform: stdenv.lib.optional enableTerminfo [ ncurses ]
+  libDeps = platform: stdenv.lib.optional enableTerminfo ncurses
     ++ [libffi]
     ++ stdenv.lib.optional (!enableIntegerSimple) gmp
     ++ stdenv.lib.optional (platform.libc != "glibc" && !targetPlatform.isWindows) libiconv;
diff --git a/pkgs/development/interpreters/php/default.nix b/pkgs/development/interpreters/php/default.nix
index 26798d676e0..0fa605a4cac 100644
--- a/pkgs/development/interpreters/php/default.nix
+++ b/pkgs/development/interpreters/php/default.nix
@@ -95,8 +95,8 @@ let
         ++ optional postgresqlSupport postgresql
         ++ optional pdo_odbcSupport unixODBC
         ++ optional pdo_pgsqlSupport postgresql
-        ++ optional pdo_mysqlSupport mysqlBuildInputs
-        ++ optional mysqliSupport mysqlBuildInputs
+        ++ optionals pdo_mysqlSupport mysqlBuildInputs
+        ++ optionals mysqliSupport mysqlBuildInputs
         ++ optional gmpSupport gmp
         ++ optional gettextSupport gettext
         ++ optional intlSupport icu
@@ -109,14 +109,14 @@ let
         ++ optional libzipSupport libzip
         ++ optional valgrindSupport valgrind;
 
-      CXXFLAGS = optional stdenv.cc.isClang "-std=c++11";
+      CXXFLAGS = optionalString stdenv.cc.isClang "-std=c++11";
 
       configureFlags = [
         "--with-config-file-scan-dir=/etc/php.d"
       ]
-      ++ optional (versionOlder version "7.3") "--with-pcre-regex=${pcre.dev} PCRE_LIBDIR=${pcre}"
-      ++ optional (versions.majorMinor version == "7.3") "--with-pcre-regex=${pcre2.dev} PCRE_LIBDIR=${pcre2}"
-      ++ optional (versionAtLeast version "7.4") "--with-external-pcre=${pcre2.dev} PCRE_LIBDIR=${pcre2}"
+      ++ optionals (versionOlder version "7.3") [ "--with-pcre-regex=${pcre.dev}" "PCRE_LIBDIR=${pcre}" ]
+      ++ optionals (versions.majorMinor version == "7.3") [ "--with-pcre-regex=${pcre2.dev}" "PCRE_LIBDIR=${pcre2}" ]
+      ++ optionals (versionAtLeast version "7.4") [ "--with-external-pcre=${pcre2.dev}" "PCRE_LIBDIR=${pcre2}" ]
       ++ optional stdenv.isDarwin "--with-iconv=${libiconv}"
       ++ optional withSystemd "--with-fpm-systemd"
       ++ optionals imapSupport [
@@ -129,7 +129,7 @@ let
         "LDAP_INCDIR=${openldap.dev}/include"
         "LDAP_LIBDIR=${openldap.out}/lib"
       ]
-      ++ optional (ldapSupport && stdenv.isLinux)   "--with-ldap-sasl=${cyrus_sasl.dev}"
+      ++ optional (ldapSupport && stdenv.isLinux) "--with-ldap-sasl=${cyrus_sasl.dev}"
       ++ optional apxs2Support "--with-apxs2=${apacheHttpd.dev}/bin/apxs"
       ++ optional embedSupport "--enable-embed"
       ++ optional mhashSupport "--with-mhash"
diff --git a/pkgs/development/libraries/java/swt/default.nix b/pkgs/development/libraries/java/swt/default.nix
index 6eb5a1f5355..b0fdca11218 100644
--- a/pkgs/development/libraries/java/swt/default.nix
+++ b/pkgs/development/libraries/java/swt/default.nix
@@ -38,8 +38,8 @@ in stdenv.mkDerivation rec {
   nativeBuildInputs = [ unzip pkgconfig ];
   buildInputs = [ jdk gtk2 libXt libXtst libXi libGLU libGL webkitgtk libsoup ];
 
-  NIX_LFLAGS = (map (x: "-L${lib.getLib x}/lib") [ xorg.libX11 pango gdk-pixbuf glib ]) ++
-    [ "-lX11" "-lpango-1.0" "-lgdk_pixbuf-2.0" "-lglib-2.0" ];
+  NIX_LFLAGS = toString (map (x: "-L${lib.getLib x}/lib") [ xorg.libX11 pango gdk-pixbuf glib ]) +
+    " -lX11 -lpango-1.0 -lgdk_pixbuf-2.0 -lglib-2.0";
 
   buildPhase = ''
     unzip src.zip -d src
diff --git a/pkgs/development/mobile/androidenv/build-tools.nix b/pkgs/development/mobile/androidenv/build-tools.nix
index 976ef141627..9e273468cd3 100644
--- a/pkgs/development/mobile/androidenv/build-tools.nix
+++ b/pkgs/development/mobile/androidenv/build-tools.nix
@@ -3,7 +3,7 @@
 deployAndroidPackage {
   inherit package os;
   buildInputs = [ autoPatchelfHook makeWrapper ] ++
-    lib.optional (os == "linux") [ pkgs.glibc pkgs.zlib pkgs.ncurses5 pkgs_i686.glibc pkgs_i686.zlib pkgs_i686.ncurses5 ];
+    lib.optionals (os == "linux") [ pkgs.glibc pkgs.zlib pkgs.ncurses5 pkgs_i686.glibc pkgs_i686.zlib pkgs_i686.ncurses5 ];
   patchInstructions = ''
     ${lib.optionalString (os == "linux") ''
       addAutoPatchelfSearchPath $packageBaseDir/lib
diff --git a/pkgs/development/mobile/androidenv/platform-tools.nix b/pkgs/development/mobile/androidenv/platform-tools.nix
index 5b4cad1f264..c39d966959a 100644
--- a/pkgs/development/mobile/androidenv/platform-tools.nix
+++ b/pkgs/development/mobile/androidenv/platform-tools.nix
@@ -3,7 +3,7 @@
 deployAndroidPackage {
   inherit package os;
   buildInputs = [ autoPatchelfHook ]
-    ++ lib.optional (os == "linux") [ pkgs.glibc pkgs.zlib pkgs.ncurses5 ];
+    ++ lib.optionals (os == "linux") [ pkgs.glibc pkgs.zlib pkgs.ncurses5 ];
   patchInstructions = lib.optionalString (os == "linux") ''
     addAutoPatchelfSearchPath $packageBaseDir/lib64
     autoPatchelf --no-recurse $packageBaseDir/lib64
diff --git a/pkgs/development/python-modules/buildbot/default.nix b/pkgs/development/python-modules/buildbot/default.nix
index 7385a329551..e627667f3ec 100644
--- a/pkgs/development/python-modules/buildbot/default.nix
+++ b/pkgs/development/python-modules/buildbot/default.nix
@@ -44,10 +44,9 @@ let
       autobahn
       pyjwt
       pyyaml
-
+    ]
       # tls
-      twisted.extras.tls
-    ];
+      ++ twisted.extras.tls;
 
     checkInputs = [
       treq
diff --git a/pkgs/development/python-modules/treq/default.nix b/pkgs/development/python-modules/treq/default.nix
index f49c7a0d243..1d488eed4e1 100644
--- a/pkgs/development/python-modules/treq/default.nix
+++ b/pkgs/development/python-modules/treq/default.nix
@@ -17,9 +17,9 @@ buildPythonPackage rec {
     incremental
     service-identity
     twisted
+  ]
     # twisted [tls] requirements (we should find a way to list "extras")
-    twisted.extras.tls
-  ];
+    ++ twisted.extras.tls;
 
   checkInputs = [
     pep8
diff --git a/pkgs/os-specific/linux/brillo/default.nix b/pkgs/os-specific/linux/brillo/default.nix
index 6d51907ea16..1262260664c 100644
--- a/pkgs/os-specific/linux/brillo/default.nix
+++ b/pkgs/os-specific/linux/brillo/default.nix
@@ -22,7 +22,7 @@ stdenv.mkDerivation rec {
 
   makeFlags = [ "PREFIX=$(out)" "AADIR=$(out)/etc/apparmor.d" ];
 
-  installTargets = "install-dist";
+  installTargets = [ "install-dist" ];
 
   meta = with stdenv.lib; {
     description = "Backlight and Keyboard LED control tool";
diff --git a/pkgs/servers/http/apache-httpd/2.4.nix b/pkgs/servers/http/apache-httpd/2.4.nix
index 63861714145..d5da6df8d68 100644
--- a/pkgs/servers/http/apache-httpd/2.4.nix
+++ b/pkgs/servers/http/apache-httpd/2.4.nix
@@ -44,10 +44,6 @@ stdenv.mkDerivation rec {
   # Required for ‘pthread_cancel’.
   NIX_LDFLAGS = stdenv.lib.optionalString (!stdenv.isDarwin) "-lgcc_s";
 
-  preConfigure = ''
-    configureFlags="$configureFlags --includedir=$dev/include"
-  '';
-
   configureFlags = [
     "--with-apr=${apr.dev}"
     "--with-apr-util=${aprutil.dev}"
@@ -60,6 +56,7 @@ stdenv.mkDerivation rec {
     "--enable-cern-meta"
     "--enable-imagemap"
     "--enable-cgi"
+    "--includedir=${placeholder "dev"}/include"
     (stdenv.lib.enableFeature proxySupport "proxy")
     (stdenv.lib.enableFeature sslSupport "ssl")
     (stdenv.lib.withFeatureAs libxml2Support "libxml2" "${libxml2.dev}/include/libxml2")
diff --git a/pkgs/tools/admin/fastlane/default.nix b/pkgs/tools/admin/fastlane/default.nix
index afb044ad583..1cdc969ea2e 100644
--- a/pkgs/tools/admin/fastlane/default.nix
+++ b/pkgs/tools/admin/fastlane/default.nix
@@ -6,15 +6,15 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [ makeWrapper ];
 
-  env = bundlerEnv {
-    name = "${pname}-${version}-gems";
-    inherit pname ruby;
-    gemdir = ./.;
-  };
-
   phases = [ "installPhase" ];
 
-  installPhase = ''
+  installPhase = let
+    env = bundlerEnv {
+      name = "${pname}-${version}-gems";
+      inherit pname ruby;
+      gemdir = ./.;
+    };
+  in ''
     mkdir -p $out/bin
     makeWrapper ${env}/bin/fastlane $out/bin/fastlane \
      --set FASTLANE_SKIP_UPDATE_CHECK 1